I experienced this exact same problem earlier this year on my 7 year old 180. Did extensive testing of the whole system including hooking up a manometer to measure gas pressure while burning. Popping was loud and frequent enough to keep you awake at night. In the end, it was the burner nozzle. Look closely at the flame openings in the burner tube. See attached picture of mine. you can see how the metal has failed around the openings and "balled up" widening the flame opening area. This reduces the gas pressure in the tube leading to the flame failure and popping. Once I replaced it problem gone and refrigerator performed perfectly. Very difficult & expensive to find in the states but found them available via eBay from UK.  Seller's name I used was guyuk10. My part number was:

Dometic/Electrolux Fridge Gas Burner Complete CBS2-DN65 289060497

We had no luck finding a three-way replacement for ours, then it settled back down and worked as usual the rest of this year, so I quit looking.

Did you also blow out the line between the refrigerator and the gas tanks? There may be some oily crud in the line that isn't between the valve and the burner. If you do that, be sure to have a bucket under the end of the gas line when you disconnect from the regulator and blow from the refrigerator end. If you have never done this, you might be surprised at the amount of oily liquid that gets blown out of the line.